I was reading the www.yfztech.com forums & came across this post by "Buddha" from Sand Mountain, UT on Dyno results for a Barker's Yamaha YFZ 450R Full Exhaust:
Well the best we could do is:
The curve is very good and a huge improvement over the PCV.
We started at 39.24 HP 25.79 TQ. Remember this is at 4400' above sea level on KBR's old Dyno. The MSD made a huge improvement with as much as 8 degress timing on the top end and as little as 5 degrees on the bottom end. I was expecting more, but that's what it is. My next mod will be boring the TB and maybe a Mmad intake cam. Also the head will probably be coming off for some expoxy. That won't be till summer as our riding season is here and I don't want any down time.
Also those numbers are with the Barker pipe. The Dasa pipe was .25HP-.50HP lower than the Barker. The Barker comes on sooner and lasts longer than the Dasa. Kind of glad I went with the Barker.
To read the entire thread on dyno results for the Barker's Yamaha YFZ 450R Full Exhaust click this link http://www.yfztech.com/forum/index.php?showtopic=25267